Hydraulic leak M4011 Backhoe

[olde harbour]

Anyone know what this is... and why it's dripping?

It's just under the controls for the backhoe - or just below the M4011 logo & made in usa sticker

 

[redmaher]

I'm assuming it's the bottom of the flow control valves.

Sent from my LG-H901 using Tapatalk

 

[olde harbour]

flow control valves sounds right...
should they be dripping?

 

[AAK]

Anyone know what this is... and why it's dripping?

It's just under the controls for the backhoe - or just below the M4011 logo & made in usa sticker

What was the cause od this leak. My tractor is doing the same thing. Please help

 

[Proctoman]

Was there ever an answer to this issue? I too am suffering.

 

[kubotafreak]

You will need to verify if that leak is not coming from higher up. May have to remove the outer cover. Just curious if you have a third function as well?

 

[Proctoman]

You will need to verify if that leak is not coming from higher up. May have to remove the outer cover. Just curious if you have a third function as well?

Thanks for the reply. I do not have a third function. I have removed the outer cover on the backhoe and the leak is coming directly from the bottom of the valve manifold, as in the pics from the first post. Is this possibly a pressure relief point? Thanks again for all the help.

 

[kubotafreak]

I asked about the 3rd function because they can easily blow the seals on the backhoe if installed wrong. You eliminated this since you said you don't. Well I would rest the backhoe bucket/outriggers on the ground, remove the cap under that first(boom) valve stack (Allen key) 10ftlbs. There should be a lip seal under the spring position cap. I would look for anything out of the ordinary. From my experience they usually leak from overpressure of the valve.(dragging/driving with boom down/miss installation of other hydraulic valves) Most of the ones I have seen bend the top plate that holds the seal down. The seal for the bottom should be similar. I would make sure I have the hookups correct on the machine end. I assume you have two hoses. One P(IN)from loader and one PB(out) to manifold/threepoint The valves have one or two reliefs each. The reliefs look like big adjustable plugs(one at top and bottom) between the hose outlet side and the spool itself. These are usually set in conjunction with the relief on the source manifold on the Backhoe valve stack.(I Wouldn't play with them unless you know-have the correct tools). The silver cap at the bottom is the spool spring positioning cap. They usually contain some return springs/ball/detents. There should not be external leaks, even if the valve relief is dumping. I do caution you not to loose any of the parts, as many are not available separate from a whole valve.$$$$ The seals are generally available as I saw from the part diagram.

It is odd you and another member both have the same issue. I wonder if these are being installed right at the dealer. Your backhoes are plumbed to the front manifold/loader valve right? Not some funny rear remote business. These add on backhoes need a good shock free source for PB hydraulic flow. Any shock loads can blow the seals. This is why they are usually plumbed second to last in the hydraulic circuit before the three point.

 

[skidnee]

First time member and first post.....ever....! No social media for this cowboy.

I hate to drag out an old thread, but I now have the leaky control valve on my backhoe attachment. It is leaking from the spring position cap. I printed out the description above, but was wondering if anyone has any more information or maybe a video? It seems quite a few folks are having this same issue, but other than kubotafreak's write-up I can't find any other info. I looked on the Kubota parts webpage and found:

SPOOL SEAL KIT

70002-00664

It's $94 and doesn't list what you get, and our dealer wasn't much help either. After I get it apart (it's one of the outrigger control valve that is leaking) and figure out what I need, I'm not sure it will be in the "Spool Seal Kit".

thanks in advance for any help!!

 

[skidnee]

Sooo I popped off the spring position cap, pretty simple, nothing scary, pretty straight forward. The cap had hydraulic fluid in it, is that normal? I cleaned up the cap, put it back together and the leak slowed substantially, now it's just an occasional drip. Still not right, but just not sure about the hydraulic fluid in the cap itself? I'm missing one to the little rubber plugs in the bottom of another spring position cap, and pretty sure they don't make those anymore, might put a small bolt/nut with rubber washers in its place.

 

[TheOldHokie]

Sooo I popped off the spring position cap, pretty simple, nothing scary, pretty straight forward. The cap had hydraulic fluid in it, is that normal? I cleaned up the cap, put it back together and the leak slowed substantially, now it's just an occasional drip. Still not right, but just not sure about the hydraulic fluid in the cap itself? I'm missing one to the little rubber plugs in the bottom of another spring position cap, and pretty sure they don't make those anymore, might put a small bolt/nut with rubber washers in its place.

What is the model number of the backhoe?

Dan

 

[skidnee]

What is the model number of the backhoe?

Dan

Thanks for responding Dan.

M4011, it's probably 3 or 4 years old but looks just like the pictures at the top of this thread.

 

[skidnee]

I did an AI search, which has at times been not even close to reality. So I was hoping someone with experience here can tell me if this is correct or not. Here is some copy and paste from AI:

If hydraulic fluid is reaching the positioner cap, that means:

The internal spool seal (between the valve body and the spool bore) has failed.

This seal is what keeps hydraulic oil in the control section and away from the positioner assembly.

When that seal fails, the oil migrates outward along the spool shaft and ends up:

• Filling the positioner cavity,
• Squeezing past the detent hardware,
• And finally leaking out through the rubber dust plug or weep hole located at the bottom of the cap.

That rubber plug is not designed to hold pressure, so even a small leak becomes a drip or stream there.

3. What part actually needs to be replaced?

To stop the leak, you must replace the spool seal kit for that valve section:

Kubota Part #70002-00664 – “Spool Seal Kit”

(This contains the O-rings and seals that keep hydraulic pressure out of the positioner cavity.)


This kit works with the existing or new spool positioner assembly (70002-00644).
Replacing the positioner alone will not stop the leak, because the leak originates upstream — at the spool/bore interface.

Would you agree with this description?? Thanks again for any help/advise, very much appreciated!!

 

[TheOldHokie]

I did an AI search, which has at times been not even close to reality. So I was hoping someone with experience here can tell me if this is correct or not. Here is some copy and paste from AI:

If hydraulic fluid is reaching the positioner cap, that means:

The internal spool seal (between the valve body and the spool bore) has failed.

This seal is what keeps hydraulic oil in the control section and away from the positioner assembly.

When that seal fails, the oil migrates outward along the spool shaft and ends up:

• Filling the positioner cavity,
• Squeezing past the detent hardware,
• And finally leaking out through the rubber dust plug or weep hole located at the bottom of the cap.

That rubber plug is not designed to hold pressure, so even a small leak becomes a drip or stream there.

3. What part actually needs to be replaced?

To stop the leak, you must replace the spool seal kit for that valve section:

Kubota Part #70002-00664 – “Spool Seal Kit”

(This contains the O-rings and seals that keep hydraulic pressure out of the positioner cavity.)


This kit works with the existing or new spool positioner assembly (70002-00644).
Replacing the positioner alone will not stop the leak, because the leak originates upstream — at the spool/bore interface.

Would you agree with this description?? Thanks again for any help/advise, very much appreciated!!

That is a surprisingly accurate description. What it leaves out is why is this a common problem on Kubota backhoes. Here is @kubotafreak's cutaway of the valve with some added annotation. As indicated the seal is between the tank core in the valve and the positioner. The seals are only designed to handle tank port pressure which is generally limited to a maximum of a few hundred PSI.

Kubota plays games with most of their backhoes and routes the tank flow back through the power beyond circuit on the tractor. If the backhoe is properly connected and the 3pt lever is kept fully down, that works fine. But if its plumbed incorrectly, the return hose is not properly connected, or someone raises the 3pt control that can generate 2000+ PSI on the tank outlet and "boom" - spool seals go bye bye. Looks like your hoe uses a true power beyond (three hose) connection to the tractor but the tank return hose can still cause a problem if not properly connected..

Dan

 

[skidnee]

Thank you Dan. I haven't had a chance to check the return hose, but I do know the 3pt lever is up...if only I had known. It seems like I had an over pressure event, although I have no idea how or when that happened....and now I'm replacing a bunch of spool seals. Makes me wonder if I didn't bump that 3pt lever at some point.

I found this video (link below) and it looks like I'll need to pull the spool valve to replace the spool valve seals...and thank you for the picture describing where they are located!

I now have two questions:

1) Do I have to pull the valve body completely off the machine and take it to the bench, or can I detach it from the frame, lean it forward and gain enough space to pull out the spool valves out the bottom of the valve body, while leaving it on the machine.

2) Since this is for an outrigger (stabilizer) valve assembly, It looks like I'll need to order SPOOL SEAL KIT 70002-00664 I'll head down to the dealer for another discussion, but it's an hours drive and I want to have all my ducks in order. At $94 for each kit, times 6 valves, bumping a lever may have cost me $600 and a bunch of repair time.....,

Thanks again for the help Dan!!

 

[TheOldHokie]

Thank you Dan. I haven't had a chance to check the return hose, but I do know the 3pt lever is up...if only I had known. It seems like I had an over pressure event, although I have no idea how or when that happened....and now I'm replacing a bunch of spool seals. Makes me wonder if I didn't bump that 3pt lever at some point.

I found this video (link below) and it looks like I'll need to pull the spool valve to replace the spool valve seals...and thank you for the picture describing where they are located!

I now have two questions:

1) Do I have to pull the valve body completely off the machine and take it to the bench, or can I detach it from the frame, lean it forward and gain enough space to pull out the spool valves out the bottom of the valve body, while leaving it on the machine.

2) Since this is for an outrigger (stabilizer) valve assembly, It looks like I'll need to order SPOOL SEAL KIT 70002-00664 I'll head down to the dealer for another discussion, but it's an hours drive and I want to have all my ducks in order. At $94 for each kit, times 6 valves, bumping a lever may have cost me $600 and a bunch of repair time.....,

Thanks again for the help Dan!!

On that hoe you have a true power beyond valve and the 3pt lever should not cause your problem. It can however cause the pump to deadhead and unload constantly at full system pressure via the maun system relief. Are all 6 valves leaking? That sounds like you were overpressuring the tank port somehow. Possibly a improperly connected tank return hose.

Dan

 

[TheOldHokie]

Is this how the tractor side plumbing is installed on your tractor?

Dan

 

[skidnee]

4 of the 6 valves are leaking....and yes that is exactly how the backhoe is plumbed. We've got 30 mph winds out here in Wyoming today...ate a little dirt tracing those hydraulic lines... )

 

[TheOldHokie]

4 of the 6 valves are leaking....and yes that is exactly how the backhoe is plumbed. We've got 30 mph winds out here in Wyoming today...ate a little dirt tracing those hydraulic lines... )

Different stste - same sentiment

https://www.youtube.com/watch?v=exu...wqsBegQIFRAB&usg=AOvVaw3JhG6BL3Cx88ikVHW7pLAy

 

[skidnee]

Thanks Dan...I'm not sure I could follow that youtube video link...it first went to a Montana game camera, with grizzly bears, moose, and a fox that was always running around with something dead in his mouth... ) (reminded me of my backyard). Messed around some more and got a great video of a guy taking apart a backhoe valve body and a kid helping him, ferkn hilarious but very helpful, then a video from 1950's on breaking down a valve body. Anyways not sure if any of these were intended to be the link you posted, but took me to some very entertaining and helpful video. My take-home message is I'll be pulling that valve body and rebuilding on the bench in the shop. Thanks again for your help!!